DRILL-7403: Validate batch checks, vector integretity in unit tests
Enhances the existing record batch checks to check all the various
batch record counts, and to more fully validate all vector types.
This code revealed that virtually all record batches have
problems: they omit setting some record count or other, they
introduce some form of vector corruption.
Since we want things to work as we make fixes, this change enables
the checks for only one record batch: the "new" scan. Others are
to come as they are fixed.
closes #1871
